In the last post I commented on the recent paper by Dall et al. (2013) and the context of its publication. As commented on by the author in response to that post, some of the results are interesting in their own right. (I was going to paste a couple of figures from the paper into this article but the publishers require a payment of over $300 to do this legally so you’ll have to download a copy of the paper yourself if you want to see the evidence.)
Figure 1 shows the frequency distribution of minute epochs during which walking was recorded at various cadences. The mean cadence was 76 steps per minute with a cadence of less than 100 steps per minute in about 80% of the minutes during which any walking was recorded. When healthy adults walk at “self-selected” speed in the gait lab they tend to walk at cadences of well over 100 steps per minute (A brief review of the previous literature in Winter (1991) suggests values between 100 and 120). We can thus see that cadence in everyday activity is very different to that during walking in the laboratory.
The paper also includes a second graph (Figure 4) showing the same data but for the sub-set of minutes when the participants walked for the full minute. This shows a mean value of 109 (±9) steps per minute which is in much better agreement with the self-selected walking speeds recorded in the laboratory. The most obvious explanation of these two graphs together is that when we walk for short bouts we do so at much slower cadences than we tend to look at in the laboratory but when we walk continuously for a minute or more that we appear to walk at similar speeds (although the graphs tends to suggest that there is more variability in this in real life than I’d expect in the laboratory).
This can be put together with the data from Orendurff et al. (2008) that shows that 90% of bouts of walking are for less than 100 steps and 75% are less than 40 steps to suggest that the walking we investigate in the gait laboratory is quite different to the walking the we use most frequently in our everyday lives. This worries some people but this misses the reason for performing clinical gait analysis as we do. We use level walking at self-selected speed because it is a well-defined stereotypical movement that we understand reasonably well. We hope that analysing it will give clinical insights into impairments of neurological, muscular or skeletal function. The ultimate hope is that if we base treatment on the results of this analysis then we will improve function in “laboratory walking” and in every day walking as well. I hope you can see that this line of reasoning does not necessarily require laboratory walking to be representative of everyday walking.
Dall, P. M., McCrorie, P. R., Granat, M. H., & Stansfield, B. W. (2013). Step Accumulation per Minute Epoch Is Not the Same as Cadence for Free-Living Adults. Med Sci Sports Exerc.
Orendurff, M. S., Schoen, J. A., Bernatz, G. C., Segal, A. D., & Klute, G. K. (2008). How humans walk: bout duration, steps per bout, and rest duration. J Rehabil Res Dev, 45(7), 1077-1089.
Winter, D. (1991). The biomechanics and motor control of human gait: Normal, Elderly and Pathological (2nd ed.). Waterloo:: Waterloo Biomechanics.
I’m not sure what the laws are in England, but in the US we have the “fair use” exemption to copyright. From Wikipedia: ” In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, news reporting, research, teaching, library archiving and scholarship.” These four factors are, as per 17 USC 106/106a:
1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
2) the nature of the copyrighted work;
3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
4) the effect of the use upon the potential market for or value of the copyrighted work.
My guess is that you would be justified in using the figure with attribution. However, and this is a big however, you may be perfectly justified in your usage of the figure, but the publisher may still make your life hell and sue you… and presuming you had the money, you would win, but your pockets are not so deep.
I’m currently in the same conundrum with respect to a commentary with regards to dynamic balance. Perhaps we should be promoting journals other than those published by Elsevier?
I actually went to the publisher’s web-site to ask permission (Wolters Kluyer who are an off-shoot of Lippincott, Williams and Wilkins). They wanted $300 to post two figures on a web-site that I’d made clear was not for profit with an estimated readership of 200 people! I suppose I could have contacted them directly and argued my case but I just gave up at that point.
I take your point about attribution though. I’ve looked back over some previous posts and I’ve not been as explicit as that as I might have been. Must try better in future!
It’s interesting that I’ve asked permission to use figures from journals for my book and various chapters I’ve written and this appears to have been virtually automatic without cost.